Boundary Shear in Smooth Rectangular Channels

Abstract

The results of some experiments are reported concerning the boundary shear stress and boundary shear force distributions in a smooth channel of rectangular cross section. An empirically derived equation is presented which gives the percentage of the total shear force carried by the walls as a function of the breadth/depth ratio. Ancillary equations are presented giving the mean wall, bed, and bed center line shear stresses as functions of aspect ratio. A comparison is made between boundary shear stress distributions in open channel and closed conduit flows at comparable aspect ratios. Certain differences are noted in both the distributions and the mean resistance coefficients on account of different secondary flow structure. The results will be useful to those engaged in resistance, sediment, or dispersion studies.